A note on the methylation of quercetagetin

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Pigments of cotton flowers. Part VIII. Constitution of Herbacitrin and Quercimeritrin

The constitution of Herbacitrin is established as the 7-glucoside of Herbacetin by methylating the glucoside through the acetyl derivative and isolating 7-hydroxy-3: 5: 8: 4'tetramethoxy flavone from the hydrolysis of the methylated glucoside. Similarly, the constitution of Quercimeritrin is confirmed as the 7-glucoside of Quercetin

The structural chemistry of naturally occurring flavones and flavonols

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Isolation and constitution of quercetagitrin, a glucoside of quercetagetin

Quercetagitrin, a monoglucoside of quercetagetin, has for the first time been isolated from the flowers of the African Marigold (Tagetes erecta). It is not a 3-glucoside since it gives a red precipitate with lead acetate and does not undergo easy hydrolysis with acids. Further it is easily oxidised in cold alkali, and after methylation the products of decomposition yield veratric acid. The glucose group, therefore, is not present in the side phenyl nucleus. By complete methylation and subsequent hydrolysis of the glucoside, a pentamethyl quercetagetin is obtained. This ether is a new compound, and differs from 3:6:7:3':4'-pentamethyl quercetagetin in all its properties, and hence the free hydroxyl group in it is in either the 6th or the 7th position. The allyl ether of this new pentamethyl quercetagetin smoothly undergoes the Claisen Rearrangement, indicating thereby that the ortho-position with respect to the allyloxy group is unsubstituted. Hence the allyl ether should be 3:5:6:3':4'-pentamethyl-7-allyl quercetagetin, and the new pentamethyl ether should have the constitution of 3:5:6:3':4'-pentamethyl quercetagetin. Consequently quercetagitrin is the 7-glucoside of quercetagetin

Reactivity of the double bond in coumarins and related α-β unsaturated carbonyl compounds Part IV. Action of bromine on coumaric acids

By the action of bromine on coumaric, 4-methylcoumaric and 5-nitrocoumaric acids in boiling glacial acetic acid solution 3:6:8-tribromocoumarin, 3:6:8-tribromo-7-methylcoumarin and 3:8-dibromo-6-nitrocoumarin have been obtained in good yield. The primary products are the dibromides of the bromo-compounds produced by the addition at the double bond, subsequent substitution in the nucleus and final ring closure. Hydrogen bromide gets slowly removed during the boiling and during the subsequent crystallisations so as to yield the above-mentioned bromocoumarins. The best method for this however is to use cold alcoholic potash. Small quantities of the lower bromination products are also produced as by-products

Constitution of butrin

On treatment with diazomethane, butrin gives rise to a monomethyl ether which yields on hydrolysis with acids a mixture of 4'-O-methylbutin and 4'-O-methylbutein, the latter being the major component. The constitutions of these two products have been established by alkaline oxidation, yielding isovanillic acid and comparison with synthetic samples. It is, therefore, concluded that butrin is 3': 7-diglucoside of butin, and thus it is the first instance of a glycoside to contain the sugar residues in two different positions amongst the group of anthoxanthins and also the first instance to carry a sugar group in the side phenyl nucleus amongst both anthoxanthin and anthocyanin pigments

Geometrical inversion in the acids derived from the coumarins. Part V. The behaviour of Psoralic and Isopsoralic acids

The stable trans acids, Psoralic and Isopsoralic acids, have been prepared from Psoralen and Isopsoralen. With concentrated sulphuric acid they undergo complex changes whereas in the presence of sunlight and aqueous mercuric chloride they yield the original pyrones. Though Isopsoralic acid undergoes ring closure more easily the difference is not great

Chemical examination of Erythrina indica

From the seeds of Erythrina indica a fixed oil and a water-soluble alkaloid have been isolated. The properties of the oil have been compared with those of the oil of the Formosan variety and found to differ in the degree of unsaturation. The alkaloid has been identified as hypaphorine. The bark contains, besides a large amount of mineral matter and resin, the same base which is also present in the leaves to a smaller extent

Colouring matter of the flowers of Hibiscus cannabinus: constitution of cannabiscetin

The colouring matter of the flower petals of Hibiscus cannabinus consists mostly of the glucoside cannabiscitrin along with small quantities of the corresponding aglucone cannabiscetin. The properties and reactions of these two substances are described along with those of some of their derivatives. Cannabiscetin forms a hexaacetate and a hexamethyl ether. It is a flavonol exhibiting similarities with gossypetin and herbacetin particularly in regard to alkali colour reactions and gossypetone reaction. It yields gallic acid on being subjected to alkali fission, its methyl ether producing trimethyl gallic acid. It is, therefore, concluded to be 3:5:8:3':4':5' hexahydroxy flavone